Medium guiding device, image forming device, image reading device and post-processing device

ABSTRACT

A medium guiding device includes an upstream side rollers pair, a downstream side rollers pair, a first rib, a second rib and an interlocking part. In a first conveying state where the medium is conveyed while being held by the upstream side rollers pair and separated from the downstream side rollers pair, the interlocking part retreats the first rib from a curved path and protrudes the second rib into the curved path. In a second conveying state where the medium is conveyed while being held by the downstream side rollers pair, the interlocking part protrudes the first rib into the curved path and retreats the second rib from the curved path.

INCORPORATION BY REFERENCE

This application is based on and claims the benefit of priority from Japanese patent application No. 2022-053679 filed on Mar. 29, 2022, which is incorporated by reference in its entirety.

BACKGROUND

The present disclosure relates to a media guiding device which guides a media to be conveyed, an image forming device, an image reading device and a post-processing device.

The image forming device may be provided with a sheet guiding device which guides a sheet being conveyed along a sheet conveyance path. The sheet guiding device includes a guiding roller which is contact with a conveying roller and driven to be rotated, and a movable rib supported by the guiding roller through a floating shaft. When the diameter of the conveying roller increases or decreases, the guiding roller and the movable rib are protruded into or retreated from the sheet conveyance path to keep the movable rib at an appropriate position to the nip between the conveying roller and the guiding roller.

Now consider a configuration in which rollers pairs are provided on the upstream and downstream sides of a curved conveyance path (a curved path). The sheet is conveyed (nip-conveyed) while being held between the upstream side rollers pair, and conveyed while being flexed along the outer diameter surface of the curved path (hereafter referred to as “a first state”). As the sheet conveying proceeds and the sheet begins to be nip-conveyed by the downstream side rollers pair while continuing the nip-conveying by the upstream side rollers pair, the sheet is pulled inward in the radial direction from the outer diameter surface of the curved path and begins to be conveyed along the inner diameter surface (hereafter, referred to as “a second state (early stage)”.). Further the sheet conveying proceeds, and when the rear edge of the sheet passes through the upstream side rollers pair (the nip-conveying is completed) and is nip-conveyed by the downstream side rollers pair (hereafter, referred to as “a second state (later stage)), the stiffness of the flexed sheet itself causes the rear edge of the sheet to spring up outward in the radial direction in the curved path. Then, the rear edge of the sheet is hit against the outer diameter surface of the curved path, generating an impact noise.

In the first state, it is preferred that the upstream side portion of the curved path is to be wider and a rib is provided in the downstream side portion of the curved path to press the sheet from the inside in the radial direction. As a result, the conveyance of the sheet along the outer diameter surface of the curved path is not inhibited, and smooth conveyance of the sheet can be ensured. In contrast, in the second state (the early and late stages), it is preferred that the downstream side portion of the curved path is to be wider and a rib is provided in the upstream side portion of the curved path to press the sheet from the outside in the radial direction. As a result, the generation of impact noise associated with the spring-up of the rear edge of the sheet can be suppressed.

However, since the above technique makes the position of the movable rib with respect to the nip constant regardless of the size of the diameter of the conveyance roller, even if the above described technique is applied to the curved path, it is not possible to suppress the generation of impact noise associated with the spring-up of the rear edge of the sheet while ensuring smooth conveyance of the sheet in both the first and second states.

SUMMARY

In accordance with one aspect of the present disclosure, a medium guiding device includes an upstream side rollers pair, a downstream side rollers pair, a first rib, a second rib and an interlocking part. The upstream side rollers pair is provided on an upstream side in a conveyance direction of the medium from an apex of a curved path included in a medium conveyance path, and rotates while holding the medium to convey the medium. The downstream side rollers pair is provided on a downstream side in the conveyance direction from the apex in the medium conveyance path, and rotates while holding the medium to convey the medium. The first rib is provided on the downstream side in the conveyance direction from the upstream side rollers pair and on the upstream side in the conveyance direction from the apex, is configured to be protruded into and retreated from the curved path from an outside in a radial direction of the curved path, and comes into contact with the medium in a protruding state into the curved path. The second rib is provided on the upstream side in the conveyance direction from the downstream side rollers pair and on the downstream side in the conveyance direction from the apex, is configured to be protruded into and retreated from the curved path from an inside in the radial direction of the curved path, and comes into contact with the medium in a protruding state into the curved path. The interlocking part interlocks the first lib and the second rib so as to protrude and retreat them into and from the curved path. In a first conveying state where the medium is conveyed while being held by the upstream side rollers pair and separated from the downstream side rollers pair, the interlocking part retreats the first rib from the curved path and protrudes the second rib into the curved path. In a second conveying state where the medium is conveyed while being held by the downstream side rollers pair, the interlocking part protrudes the first rib into the curved path and retreats the second rib from the curved path.

In accordance with one aspect of the present disclosure, an image forming device includes the medium guiding device.

In accordance with one aspect of the present disclosure, an image reading device includes the medium guiding device

In accordance with one aspect of the present disclosure, a post-processing device includes the medium guiding device.

The above and other objects, features, and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present disclosure is shown by way of illustrative example.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view showing an inner structure of a copying machine according to one embodiment of the present disclosure.

FIG. 2 is a front view showing a media guiding device according to the first embodiment of the present disclosure.

FIG. 3 is a front view showing the media guiding device (the first conveying state) according to the first embodiment of the present disclosure.

FIG. 4 is a front view showing the media guiding device (the second conveying state (the early stage)) according to the first embodiment of the present disclosure.

FIG. 5 is a front view showing the media guiding device (the second conveying state (the later stage)) according to the first embodiment of the present disclosure.

FIG. 6 is a front view showing the media guiding device (the first conveying state) according to the second embodiment of the present disclosure.

FIG. 7 is a front view showing the media guiding device (the second conveying state) according to the second embodiment of the present disclosure.

FIG. 8 is a front view showing the media guiding device (the first conveying state) according to the third embodiment of the present disclosure.

FIG. 9 is a front view showing the media guiding device (the second conveying state) according to the third embodiment of the present disclosure.

FIG. 10 is a schematic view (front view) showing an inner structure of a copying machine according to the first modified example of the first to third embodiments of the present disclosure.

FIG. 11 is a schematic view (front view) showing an inner structure of a copying machine (including a post-processing device) according to the second modified example of the first to third embodiments of the present disclosure.

DETAILED DESCRIPTION

Hereinafter, with reference to the attached drawings, one embodiment of the present disclosure will be described. Fr, Rr, L, R, U and D marked in the drawings refer to the front, back, left, right, upper and lower. The directional and positional terms are used in the specification for convenience of explanation and are not intended to limit the technical scope of this disclosure.

[Multifunctional Peripheral] With reference to FIG. 1 , a multifunctional peripheral 1 will be described. FIG. 1 is a schematic view (a front view) showing an inner structure of the multifunctional peripheral 1.

The multifunctional peripheral 1 includes an image forming device 1A which forms an image on a sheet P (medium) by an electrophotographic method and an image reading device 1B which optically reads an image of a document and converts it into electronic data.

[Image forming device] The image forming device 1A includes a device main body 2 constituting an approximately parallelepiped appearance. In the lower portion in the device main body 2, a sheet feeding cassette 3 in which the sheet P is stored is detachably provided, and a sheet discharge tray 4 is provided on the upper surface of the device main body 2. The sheet P as an example of a medium is not limited to a paper sheet, but may be a resin sheet (film) or other material that can be elastically flexed. In the description of the image forming device 1A, the direction in which the sheet P is conveyed is referred to as “a conveyance direction”, and “the upstream”, “the downstream” and similar terms refer to “the upstream”, “the downstream” and similar concepts in the conveyance direction.

The image forming device 1A includes a toner container 10, a photosensitive drum 11, a charging device 12, a developing device 13, a transferring roller 14, an optical scanning device 15 and a fixing device 16. The toner container 10 is disposed in the upper left portion in the device main body 2, and contains a black toner (developer), for example. The photosensitive drum 11 is provided in the middle of a first conveyance path 5 extending from the sheet feeding cassette 3 to the sheet discharge tray 4, and is driven to be rotated around an axis by a motor (not shown). The charging device 12, the developing device 13 and the transferring roller 14 are disposed around the photosensitive drum 11 in the order of the image forming process. The transferring roller 14 comes into contact with the photosensitive drum 11 from below to form a transfer nip. The optical scanning device 15 is provided above the photosensitive drum 11. The fixing device 16 is provided in the downstream portion of the first conveyance path 5.

The upstream side portion of the first conveyance path 5 is curved in an approximately U shape, and a sheet feeding rollers pair 40 is provided at the upstream end of the curved portion to feed the sheet P stored in the sheet feeding cassette 3 to the first conveyance path 5. A conveying rollers pair 41 is provided at the downstream end of the curved portion of the first conveyance path 5, and a registration rollers pair 43 is provided on the downstream side of the conveying rollers pair 41. The registration rollers pair 43 temporarily stops the conveyed sheet P to correct a skew of the sheet P (skew correction). In addition, inside the device main body 2, a second conveyance path 6 branching at the downstream side portion of the first conveyance path 5 and merging with the upstream side portion of the first conveyance path 5 is provided. On the second conveyance path 6, a plurality of conveying rollers pairs 42 for conveying the sheet P are provided.

[Image Forming Processing] The operation of the image forming device 1A will be described. A controller (not shown) that controls the multifunctional peripheral 1 collectively performs image forming processing based on image data input from an external terminal, for example, as follows.

The charging device 12 charges the surface of the photosensitive drum 11, and the optical scanning device 15 emits scanning light based on the image data to form an electrostatic latent image on the surface of the photosensitive drum 11. The developing device 13 develops the electrostatic latent image on the surface of the photosensitive drum 11 into a toner image using the toner supplied from the toner container 10. The sheet feeding rollers pair 40 feeds the sheet P from the sheet feeding cassette 3 one by one to the first conveyance path 5. The sheet P is conveyed along the first conveyance path 5, the skew of the sheet P is corrected by the registration rollers pair 43, and the sheet P enters the transfer nip. The transferring roller 14 transfers the toner image on the photosensitive drum 11 to the sheet P passing through the transfer nip, and the fixing device 16 thermally fixes the toner image to the sheet P. In the case of single-sided printing, the sheet P is discharged to the sheet discharge tray 4.

In the case of duplex printing, the sheet P is switched back at the downstream end of the first conveyance path 5 and sent to the second conveyance path 6, conveyed by the conveying rollers pair 42 and returned to the first conveyance path 5 again. Then, an image is formed on the back side surface of the sheet P in the same process as described above, and the double-sided printed sheet P is discharged to the sheet discharge tray 4.

[Image Reading Device] The image reading device 1B includes a reading part 20 and a document conveying device 21. The reading part 20 is mounted on the upper surface of the device main body 2, and is arranged above the sheet discharge tray 4 across a sheet discharge space. The document conveying device 21 is mounted on the upper surface of the reading part 20.

<Reading Part> The reading part 20 includes an optical scanning unit 22, a reflection unit 23 and an image sensor 24. The optical scanning unit 22 irradiates the document placed on a contact glass 25A or a platen glass 25B with light. The reflection unit 23 reflects the light reflected by the document toward the image sensor 24. When reading the document placed on the platen glass 25B, the optical scanning unit 22 and the reflection unit 23 move so that the optical path length from the document to the image sensor 24 is constant. The image sensor 24 photoelectrically converts the input light.

<Document Conveying Device> The document conveying device 21 includes a document pressing part 26, a supply tray 27, a discharge tray 28 and a conveying part 29. In the description of the image reading device 1B, the direction in which the sheet P is conveyed is referred to as “a conveyance direction”, and “the upstream”, “the downstream” and similar terms refer to “the upstream”, “the downstream” and similar concepts in the conveyance direction.

The document pressing part 26 is turnably (openable and closable) attached to the rear portion of the upper surface of the reading part 20 via a hinge (not shown). The supply tray 27 extends from the conveying part 29 obliquely upward in the right direction, and the discharge tray 28 is provided on the upper surface of the document pressing part 26. The supply tray 27 is disposed away upward from the discharge tray 28.

Inside the conveying part 29, an approximately U-shaped curved document conveyance path 30 is formed so as to connect the supply tray 27 to the discharge tray 28. At the upstream end of the document conveyance path 30, a document feeding part 31 is provided to separate the documents placed on the supply tray 27 one by one and then sent them to the document conveyance path 30. A plurality of document conveying rollers pairs 32 are provided in the middle portion of the document conveyance path 30 (between the document feeding part 31 and the contact glass 25A), and a document discharge rollers pair 33 is provided at the downstream end of the document conveyance path 30.

[Image Reading Processing] The operation of the image reading device 1B will be described. When the document is placed on the supply tray 27 with the document pressing part 26 closed, a controller performs image reading processing as follows. The document placed on the supply tray 27 is the sheet P, but the document placed on the platen glass 25B is not limited to the sheet P, and may be a booklet, a card or the like.

The document feeding part 31 feeds the document placed on the supply tray 27 to the document conveyance path 30. The document is conveyed on the contact glass 25A by the document conveying rollers pair 32. The optical scanning unit 22 irradiates the document passing on the contact glass 25A with light, and the light reflected by the document is input to the image sensor 24 and converted into an electrical signal. Thus, the image of the document is read as image data. The document discharge rollers pair 33 sends the document passed through the contact glass 25A to the discharge tray 28.

Next, when the document pressing part 26 is opened and the document is placed on the platen glass 25B, the controller performs image reading processing as follows. The optical scanning unit 22 irradiates the document on the platen glass 25B with light while moving to the right. The light reflected by the document is input to the image sensor 24, and converted into an electrical signal, so that the image of the document is read as image data.

The image data read as described above is stored in the storage of the controller, and the controller performs the image forming processing (printing) described above. The image data may be stored in an external terminal without being printed.

By the way, it is preferable to make the multifunctional peripheral 1 small in consideration of installation in a limited space such as an office. For this reason, in the small size image forming device 1A, the conveyance paths 5 and 6 along which the sheet P is conveyed are often formed to be meandered (see FIG. 1 ). As an example, a curved path 6A along which the sheet P is conveyed while being flexed is formed in the downstream side portion (including the merging portion with the first conveyance path 5) of the second conveyance path 6. Of the plurality of conveying rollers pairs 42 described above, the conveying rollers pair 42 arranged on the most downstream side is provided in the upstream portion of the curved path 6A (or may be the end portion of the straight portion of the second conveyance path 6), and the registration rollers pair 43 is provided in the downstream portion of the curved path 6A (or may be the straight portion of the first conveyance path 5). Note that the curved path 6A refers to the area where the sheet P is conveyed while being flexed in the downstream side portion of the second conveyance path 6 (including a part of the first conveyance path 5) (for example, the area indicated by the two-dotted chain line in FIG. 2 ). In addition, the curved path 6A may be an arc-shaped path, a polygonal path in which multiple straight paths are connected while being bent finely, or a combination of these paths, as long as the sheet P (medium) is conveyed while being flexed. In the description of the specification, the conveying rollers pair 42 is referred to as the upstream side rollers pair 42, and the registration rollers pair 43 is referred to as the downstream side rollers pair 43.

The upstream side rollers pair 42 and the downstream side rollers pair 43 convey the sheet P by rotating while holding the sheet P (hereafter, it is also called “nip-conveying”). In each of the rollers pairs 42 and 43, one roller is driven by a motor or the like, and the other roller is driven, but not limited to this, both rollers may be driven. In the description of the specification, a state in which the sheet P is nip-conveyed by the upstream side rollers pair 42 and away from the downstream side rollers pair 43 (not nip-conveyed by the downstream side rollers pair 43) is called a first conveying state S1 (see FIG. 3 ). On the other hand, regardless of whether the sheet P is nip-conveyed by the upstream side rollers pair 42, a state in which the sheet P is nip-conveyed by the downstream side rollers pair 43 is called a second conveying state S2 (see FIG. 4 and FIG. 5 ).

In the first conveying state S1, the sheet P is conveyed while being flexed along the radial outer surface (the outer diameter surface 6B) of the curved path 6A by its own stiffness (see FIG. 3 ). Then, when it is changed from the first conveying state S1 to the second conveying state S2 (the early stage of the second conveying state S2), that is, when the sheet P begins to be nip-conveyed by the downstream side rollers pair 43 while continuing the nip conveying by the upstream side rollers pair 42, the sheet P is pulled radially inward from the outer diameter surface 6B of the curved path 6A by the conveying force by the downstream side rollers pair 43, and begins to be conveyed along the inner diameter surface 6C of the curved path 6A (see FIG. 4 ). Further, as the conveying of the sheet P proceeds, when the rear end of the sheet P passes through the upstream side rollers pair 42 (the nip-conveying by the upstream side rollers pair 42 is completed) and it is changed to the nip-conveying by the downstream side rollers pair 43 (the later stage of the second conveying state S2), the rear end of the sheet P is sprung up from the inside to outside in the radial direction of the curved path 6A owing to the stiffness (restoring force) of the sheet P flexed along the inner diameter surface 6C (see FIG. 5 ). Then, the rear end of the sheet P is hit against the outer diameter surface 6B of the curved path 6A, and an impact noise is generated.

In the first conveying state S1, it is preferred to make the upstream side portion of the curved path 6A wide so as to press the sheet P from the inside in the radial direction in the downstream side portion of the curved path 6A. Thus, it becomes possible to ensure smooth conveying of the sheet P without inhibiting the conveying of the sheet P along the outer diameter surface 6B of the curved path 6A. On the other hands, in the second conveying state S2, it is preferred to make the downstream side portion of the curved path 6A wide so as to press the sheet P from the outside in the radial direction in the upstream side portion of the curved path 6A. Thus, it becomes possible to suppress the generation of impact noise associated with the springing of the rear end of the sheet P. Therefore, the image forming device 1A is provided with a medium guiding device 35 which suppresses the generation of impact noise associated with the springing of the rear end of the sheet P while ensuring the smooth conveying of the sheet P along the curved path 6A.

[Medium Guiding Device] The medium guiding device 35 according to the first embodiment will be described with reference to FIG. 2 and FIG. 3 . FIG. 2 is a front view showing the medium guiding device 35. FIG. 3 is a front view showing the medium guiding device 35 (in the first conveying state S1).

As shown in FIG. 2 , the medium guiding device 35 includes the upstream side rollers pair 42, the downstream side rollers pair 43, a first rib 44, a second rib 45 and an interlocking part 46.

<Upstream Side Rollers Pair, Downstream Side Rollers Pair> As shown in FIG. 2 , the upstream side rollers pair 42 (the conveying rollers pair 42) is provided on the upstream side of the apex 6T of the curved path 6A in the second conveyance path 6. The downstream side rollers pair 43 (the registration rollers pair 43) is provided on the downstream of the apex 6T in the second conveyance path 6. Specifically, the upstream side rollers pair 42 is provided on the slightly downstream side of the upstream end of the curved path 6A, and the downstream side rollers pair 43 is provided at the downstream end of the curved path 6A (or the straight portion of the first conveyance path 5). In FIG. 2 , the apex 6T of the curved path 6A refers to the most leftward projecting portion, but it does not strictly refer to only one point but to the area including a certain range.

<First Rib, Second Rib> The first rib 44 is disposed between the upstream side rollers pair 42 and the apex 6T, and the second rib 45 is disposed between the apex 6T and the downstream side rollers pair 43. The first rib 44 is provided so as to protrude into and retreat from the curved path 6A from the outside in the radial direction of the curved path 6A on the downstream side of the upstream side rollers pair 42 and on the upstream side of the apex 6T. The second rib 45 is provided so as to protrude into and retreat from the curved path 6A from the inside in the radial direction of the curved path 6A on the upstream side of the downstream side rollers pair 43 and on the downstream side of the apex 6T. The first rib 44 and the second rib 45 are formed in an approximately cylindrical shape (an approximately disk-shaped), and come into contact (are contactable) with the sheet P while protruding into the curved path 6A. Although details will be described later, the first rib 44 and the second rib 45 are rotatably provided around the axes in contact with the sheet P. Needless to say, openings are formed in the outer diameter surface 6B and the inner diameter surface 6C of the curved path 6A to allow the first rib 44 and the second rib 45 to be protruded and retreated.

<Interlocking Part> The interlocking part 46 is provided in the rear portion (or the front portion) of the device main body 2 (the curved path 6A) so as not to inhibit the conveying of the sheet P. The interlocking part 46 has a function of interlocking the first rib 44 and the second rib 45 to protrude and retreat them inro and from the curved path 6A. Specifically, as shown in FIG. 3 , the interlocking part 46 is a so-called link mechanism, and has a first link part 51, a second link part 52 and a biasing member 53.

(First Link Part) The first link part 51 is formed in an L-shape (or T-shape) and made of a metal plate, for example, and is attached to the first rib 44. The first rib 44 is supported by one end of the first link part 51 rotatably around an axis. A first shaft 51A is provided in the bent portion of the first link part 51, and the first link part 51 is supported by the device main body 2 (or a member constituting the curved path 6A) via the first shaft 51A. The first link part 51 is provided turnably around the first shaft 51A. On the other end of the first link part 51, an approximately cylindrical interlocking convex part 51B is protruded.

(Second Link Part) The second link part 52 is formed in an I-shape and made of a metal plate, for example, and is attached to the second rib 45. The second rib 45 is supported by one end of the second link part 52 rotatably around an axis. A second shaft 52A is provided in one end of the second link part 52, and the second link part 52 is supported by the device main body 2 (or a member constituting the curved path 6A) via the second shaft 52A. The second link part 52 is provided turnably around the second shaft 52A. An interlocking groove 52B extending obliquely is formed on the portion from the center to the other end of the second link part 52. The interlocking convex part 51B of the first link part 51 is slidably inserted into the interlocking groove 52B. When the interlocking convex part 51B is inserted into the interlocking groove 52B, the second link part 52 is coupled to the first link part 51 turnably and slidably.

(Biasing Member) The biasing member 53 is a so-called tension coil spring, and is installed between the other end of the second link part 52 and the device main body 2. The biasing member 53 biases (pulls) the other end of the second link part 52 inward in the radial direction. In other words, the biasing member 53 biases the second rib 45 so as protrude into the curved path 6A indirectly via the second link part 52. Note that the biasing member 53 may be regarded as indirectly biasing the first rib 44 so as to retreat from the curved path 6A via the first link part 51 engaged with the second link part 52.

[Operation of Medium Guiding Device] Next, with reference to FIG. 3 to FIG. 5 , the operation of the medium guiding device 35, that is the first rib 44 and the second rib 45 will be described. FIG. 4 is a front view showing the medium guiding device 35 (in the second conveying state (the early stage). FIG. 5 is a front view showing the medium guiding device 35 (in the second conveying state (the late stage).

<First Conveying State> First, the first conveying state S1 in which the sheet P is nip-conveyed by the upstream side rollers pair 42 but not nip-conveyed by the downstream side rollers pair 43 will be described. As shown in FIG. 3 , in the first conveying state S1, the interlocking part 46 retreats the first rib 44 from the curved path 6A and protrudes the second rib 45 into the curved path 6A. Specifically, the biasing force of the biasing member 53 causes the first link part 51 and the second link part 52 to turn such that the first rib 44 retreats from the curved path 6A and the second rib 45 protrudes into the curved path 6A. At this time, the interlocking convex part 51B of the first link part 51 abuts against the other end (the end opposite to the second rib 45) of the interlocking groove 52B of the second link part 52. The fact that the first rib 44 retreats from the curved path 6A does not require that the first rib 44 completely retreats from the curved path 6A, but means that the first rib 44 may protrude slightly from the outer diameter surface 6B of the curved path 6A. In addition, the fact that the second rib 45 protrudes into the curved path 6A means a state in which the second rib 45 is brought into slight contact with the sheet P to bring it along the outer diameter surface 6B of the curved path 6A without inhibiting the conveying of the sheet P. Even when the sheet P is not conveyed (the image forming processing is not performed and stopped), it is set in the first conveying state S1.

Since the first rib 44 retreats from the curved path 6A, the space between the inner diameter surface 6C and the outer diameter surface 6B is widened in the upstream side portion of the curved path 6A. This allows the sheet P to enter the curved path 6A smoothly. The sheet P entering the curved path 6A is pressed against the outer diameter surface 6B of the curved path 6A, and conveyed while being flexed along (in contact with) the outer diameter surface 6B. Since the second rib 45 protrudes into the curved path 6A, it comes into contact (or is made contactable (not always contacted)) the inner surface of the sheet P conveyed along the outer diameter surface 6B. Thus, the sheet P conveyed along the outer diameter surface 6B of the curved path 6A can be guided. The second rib 45 guides the sheet P while rotating around the axis when it comes into contact with the sheet P.

<Second Conveying State> Next, the second conveying state S2 in which the sheet P is nip-conveyed by the downstream side rollers pair 43 will be described. As shown in FIG. 4 , in the second conveying state S2, the interlocking part 46 protrudes the first rib 44 into the curved path 6A and retreats the second rib 45 from the curved path 6A. To explain in detail, in the early stage of the second conveying state S2, when the sheet P begins to be nip-conveyed by the downstream side rollers pair 43 while continuing the nip-conveying by the upstream side rollers pair 42, the sheet P begins to be pulled inside in the radial direction from the outer diameter surface 6B of the curved path 6A and to be conveyed along the inner diameter surface 6C. Then, the second rib 45 is pressed by the conveyed sheet P as shown by the blank arrow in FIG. 4 , and is retreated from the curved path 6A against the biasing force of the biasing member 53 while turning the second link part 52 (in the clockwise direction in FIG. 4 ). As the second link part 52 turns around the second shaft 52A, the first link part 51 is turned around the first shaft 51A (in the counterclockwise direction in FIG. 4 ) while sliding the interlocking convex part 51B toward the second rib 45 along the interlocking groove 52B of the second link part 52. That is, the first link part 51 is interlocked with the second link part 52, and is turned so as to protrude the first rib 44 into the curved path 6A while sliding relative to the second link part 52. At this time, the interlocking convex part 51B of the first link part 51 abuts against one end (the side of the second rib 45) of the interlocking groove 52B of the second link part 52.

The fact that the second rib 45 retreats from the curved path 6A does not require that the second rib 45 completely retreats from the curved path 6A, but means that the second rib 45 may protrude slightly from the inner diameter surface 6C of the curved path 6A. In addition, the fact that the first rib 44 protrudes into the curved path 6A means a state in which the first rib 44 is brought into slight contact with the sheet P to bring the sheet P along the inner diameter surface 6C of the curved path 6A without inhibiting the conveying of the sheet P.

In the early stage of the second conveying state S2, because the second rib 45 retreats from the curved path 6A, the space between the inner diameter surface 6C and the outer diameter surface 6B is widened in the downstream side portion of the curved path 6A. This ensures smooth conveying of the sheet P along (in contact with) the inner diameter surface 6C of the curved path 6A. In addition, since the first rib 44 protrudes into the curved path 6A, it comes into contact with (or is made contactable (not always contacted with)) the outer surface of the sheet P conveyed along the inner diameter surface 6C. Thus, the sheet P conveyed along the inner diameter surface 6C of the curved path 6A can be guided. When the first rib 44 comes into contact with the sheet P, it guides the sheet P while rotating around the axis.

As shown in FIG. 5 , when the rear end of the paper P passes through the upstream side rollers pair 42 and it is changed to the later stage of the second conveying state S2, the rear end of the sheet P is caused to be sprung up outward in the radial direction of the curved path 6A owing to the stiffness (restoring force) of the sheet P flexed along the inner diameter surface 6C (see the dashed line arrow in FIG. 5 ). However, since the first rib 44 protrudes into the curved path 6A as described above, the rear side of the sheet P comes into contact with the first rib 44 to be prevented from springing up.

When the conveying of the sheet P proceeds and the pressing of the second rib 45 by the sheet P is released, the second link part 52 is biased by the biasing member 53 to be turned (in the counterclockwise direction in FIG. 3 ) so as to protrude the second rib 45 into the curved path 6A. The first link part 51 is interlocked with the second link part 52 to be turned (in the clockwise direction in FIG. 3 ) so as to retract the first rib 44 from the curved path 6A.

In the medium guiding device 35 according to the first embodiment described above, in the first conveying state S1, the interlocking part 46 retracts the first rib 44 from the curved path 6A and protrudes the second rib 45 into the curved path 6A (see FIG. 3 ). With this configuration, the first rib 44 does not obstruct the sheet P (medium) conveyed along the outer diameter surface 6B of the curved path 6A. In addition, the second rib 45 comes into contact with the sheet P from the inside in the radial direction so as to guide the sheet P conveyed along the outer diameter surface 6B of the curved path 6A. In the medium guiding device 35, in the second conveying state S2, the interlocking part 46 protrudes the first rib 44 into the curved path 6A and retreats the second rib 45 from the curved path 6A (see FIG. 4 and FIG. 5 ). With this configuration, since the first rib 44 comes into contact with the sheet P from the outside in the radial direction, the rear side portion of the sheet P passing through the upstream side rollers pair 42 can be pressed downward so as not to spring up. Also, the second rib 45 does not obstruct the sheet P conveyed along the inner diameter surface 6C of the curved path 6A. As a result, it is possible to suppress the generation of impact noise associated with the springing up of the rear end of the sheet P while ensuring the smooth conveying of the sheet P in the curved path 6A.

In the medium guiding device 35 according to the first embodiment, the interlocking part 46 includes the link mechanism, and the link mechanism is activated by using the force that the sheet P is nip-conveyed by the downstream side rollers pair 43 and pulled from the outer diameter surface 6B of the curved path 6A to the inner diameter surface 6C. With this configuration, it becomes possible to interlock the first rib 44 and the second rib 45 so as to drive them in such a way that the protruding state and the retreating state are reversed each other without using a power source such as a motor. In addition, sensors to detect the driving timing of the two ribs 44 and 45 and a controller to control the power source and the sensors are not needed. Thus, the manufacturing cost and running cost such as power consumption of the medium guiding device 35 can be reduced.

In addition, according to the medium guiding device 35 according to the first embodiment, the ribs 44 and 45 rotate in contact with the sheet P, so that the conveying of the sheet P is not inhibited and smooth conveying of the sheet P can be ensured.

In the medium guiding device 35 according to the first embodiment, the biasing member 53 is a tension coil spring which pulls the second link part 52, but a compression coil spring which pushes the second link part 52 can be adopted by changing the arrangement (not shown). The biasing member 53 may be provided to pull or push the first link part 51 instead of the second link part 52 (not shown). The biasing member 53 is not limited to a coil spring, but may be a leaf spring or an elastic body such a rubber body (not shown).

Also, in the medium guiding device 35 according to the first embodiment, the biasing member 53 indirectly biases the second rib 45 through the second link part 52, but this disclosure is not limited to this. For example, if the first rib 44 (or the second rib 45) may be provided non-rotatably, the biasing member 53 may be connected to the first rib 44 (or the second rib 45) to directly bias the first rib 44 (or the second rib 45) (not shown).

In the medium guiding device 35 according to the first embodiment, the first link part 51 is provided with the interlocking convex part 51B and the second link part 52 is provided with the interlocking groove 52B. However, it is not limited to this, the first link part 51 may be provided with the interlocking groove 52B and the second link part 52 may be provided with the interlocking convex part 51B (not shown).

In addition, in the medium guiding device 35 according to the first embodiment, the interlocking part 46 has a configuration in which the first rib 44 and the second rib 45 are interlocked to protrude and retreat them without using any other power source, but this disclosure is not limited to this. For example, the biasing member 53 may be omitted, and the interlocking part 46 may be provided with a driving part (not shown) such as a solenoid (a modified example of the first embodiment). In this case, for example, the tip of the plunger of the solenoid may be rotatably connected to the first link part 51 or the second link part 52, and the solenoid is controlled by the controller to reciprocate the plunger such that the link parts 51 and 52 are turned to protrude and retreat each of the ribs 44 and 45 (not shown). The interlocking part 46 may include a detection part such as a reflection type or transmission type optical sensor, for example, and the driving part such as a solenoid may be driven at the timing when the detection part detects the sheet P passed through the downstream side rollers pair 43.

[Another Embodiments] Another embodiments will be described below with reference to FIG. 6 to FIG. 9 . FIG. 6 is a front view showing the medium guiding device 36 (in the first conveying state S1) according to the second embodiment. FIG. 7 is a front view showing the medium guiding device 36 (in the second conveying state S2) according to the second embodiment. FIG. 8 is a front view showing the medium guiding device 37 (in the first conveying state S1) according to the third embodiment. FIG. 9 is a front view showing the medium guiding device 37 (in the second conveying state S2) according to the third embodiment. In the following explanation (including the modified examples), the same marks are used for the same or corresponding configurations as those of the medium guiding device 35 according to the first embodiment, and the explanation of them is omitted.

[Second Embodiment] As shown in FIG. 6 , in the medium guiding device 36 according to the second embodiment, an interlocking part 47 includers a driving part 61, a detecting part 62 and a biasing member 63 instead of the link mechanism.

(Driving Part) The driving part 61 is, for example, a servo motor capable of controlling the rotation angle of the driving shaft 61A. The driving part 61 is electrically connected to the controller of the multifunctional peripheral 1, and controlled by the controller. An arm part 61B is attached to the driving shaft 61A of the driving part 61, and the first rib 44 is rotatably supported on the tip portion of the arm part 61B. The driving part 61 turns the arm part 61B (the driving shaft 61A) to protrude and retreat the first rib 44 into and from in the curved path 6A.

(Detecting Part) The detecting part 62 is, for example, a transmission type optical sensor in which a light emitting part and a light receiving part are arranged facing each other, and is provided near the second rib 45. The detecting part 62 is electrically connected to the controller of the multifunctional peripheral 1, and transmits a detection signal to the controller. The second rib 45 described above is rotatably supported by a support part 64, and the support part 64 is slidably supported by the device main body 2 so as to cause the second rib 45 to protrude into and retreat from the curved path 6A. When the second rib 45 is retreated from the curved path 6A, a light shielding piece 64A formed in the support part 64 enters between the light emitting part and the light receiving part to block the light emitted from the light emitting part (see FIG. 7 ). Thus, the detecting part 62 detects the second rib 45 retracted from the curved path 6A.

(Biasing Member) The biasing member 63 is, for example, a compression coil spring, and is provided so as to be wound around the support part 64. One end of the biasing member 63 comes into contact with the flange 64B of the support part 64, and the other end of the biasing member 63 comes into contact with the device main body 2. The biasing member 63 biases the second rib 45 through the support part 64 so as to protrude into the curved path 6A.

Although the controller is a component of the multifunctional peripheral 1, it may be regarded as a component of the medium guiding device 36 or the driving part 61. In addition, a dedicated controller for the medium guiding device 36 (the driving part 61) may be provided separately from the controller of the multifunctional peripheral 1, and the driving part 61 and the detecting part 62 may be controlled by the dedicated controller (not shown).

[Operation of Medium Guiding Device] Next, the operation of the medium guiding device 36 (the interlocking part 47) will be briefly described.

As shown in FIG. 6 , in the first conveying state S1, the driving part 61 retreats the first rib 44 from the curved path 6A, and the second rib 45 is biased by the biasing member 63 to protrudes into the curved path 6A. Specifically, the detecting part 62 sends a detection signal indicating that the second rib 45 (the shielding piece 64A) retreated from the curved path 6A is not detected, to the controller, and the controller receives the detection signal (the detection result) from the detecting part 62 and controls the driving part 61 to retract the first rib 44 from the curved path 6A (or keep the retreated state).

As shown in FIG. 7 , in the second conveying state S2, the second rib 45 is pushed by the conveyed sheet P and retreated from the curved path 6A against the biasing force of the biasing member 63, and the driving part 61 protrudes the first rib 44 into the curved path 6A based on that the detecting part 62 detects the retreated second rib 45 (the light shielding piece 64A). Specifically, the detecting part 62 sends a detection signal indicating that the second rib 45 retreated from the curved path 6A is detected, to the controller, and the controller receives the detection signal (the detection result) from the detecting part 62, and controls the driving part 61 to protrude the first rib 44 into the curved path 6A (or keep the protruding state).

When the conveying of the sheet P proceeds and the pushing of the second rib 45 by the sheet P is released, the second rib 45 is biased by the biasing member 63 and protrudes into the curved path 6A (see FIG. 6 ). Since the detecting part 62 no longer detects the second rib 45, the controller controls the driving part 61 to retreat the first rib 44 from the curved path 6A (see FIG. 6 ).

In the medium guiding device 36 according to the second embodiment described above, in the first conveying state S1, the driving part 61 retreats the first rib 44 and the second rib 45 is biased by the biasing member 63 to be protruded, and in the second conveying state S2, the driving part 61 protrude the first rib 44 and the second rib 45 is pushed by the sheet P to be retreated. With this configuration, the same effect as that of the medium guiding device 35 according to the first embodiment can be obtained, for example, the generation of impact noise associated with the springing up of the rear end of the sheet P can be suppressed while ensuring the smooth conveying of the sheet P in the curved path 6A. In addition, according to the medium guiding device 36 according to the second embodiment, since the first rib 44 is configured to protrude and retreat by receiving the driving force of the driving part 61 apart from the protruding and retreating operation of the second rib 45, for example, the timing of protruding the first rib 44 can be made earlier (or later), or the protruding amount of the first rib 44 (including not protruding) can be adjusted according to the thickness (stiffness) and type of the sheet P.

In the medium guiding device 36 (the interlocking part 47) according to the second embodiment, the driving part 61 is a servo motor, but it is not limited to this, and may be, for example, a solenoid capable of reciprocating a plunger (not shown). The detecting part 62 is not limited to a transmission-type light sensor, but may be, for example, a reflection-type light sensor that detects light reflected by the light shielding piece 64A, or a microswitch or the like pushed by the support part 64 (not shown). The biasing member 63 is not limited to a coil spring, but may be a leaf spring or an elastic body such as a rubber body (not shown).

[Third Embodiment] As shown in FIG. 8 , in the medium guiding device 37 according to the third embodiment, the interlocking part 48 includes a first driving part 71, a second driving part 72 and a detecting part 73.

(First Driving Part, Second Driving Part) The first driving part 71 (a first driving shaft 71A, a first arm 71B) and the second driving part 72 (a second driving shaft 72A, a second arm 72B) have the same structure as the driving part 61 (the driving shaft 61A, the arm 61B) of the medium guiding device 36 according to the second embodiment. The first driving part 71 causes the first rib 44 to protrude into and retreat from the curved path 6A, and the second driving part 72 causes the second rib 45 to protrude into and retreat from the curved path 6A.

(Detecting Part) The detecting part 73 is, for example, a reflection-type optical sensor in which a light emitting part and a light receiving part are arranged side by side, and is provided near the downstream side of the downstream side rollers pair 43. The detecting part 73 is electrically connected to the controller of the multifunctional peripheral 1, and transmits a detection signal to the controller. When the front portion of the sheet P passes through the downstream side rollers pair 43, the light emitted from the light emitting part is reflected on the sheet P and is incident on the light receiving part. Thus, the detecting part 73 detects that the downstream side rollers pair 43 is conveying the sheet P.

[Operation of Media Guiding Device] Next, the operation of the medium guiding device 37 (the interlocking part 48) will be briefly described.

As shown in FIG. 8 , in the first conveying state S1, the first driving part 71 retreats the first rib 44 from the curved path 6A, and the second driving part 72 protrudes the second rib 45 into the curved path 6A. Specifically, the detecting part 73 sends a detection signal indicating that the sheet P is not detected, to the controller, and the controller, upon receiving the detection signal (the detection result) from the detecting part 73, controls the first driving part 71 to retreat the first rib 44 from the curved path 6A, and controls the second driving part 72 to protrude the second rib 45 into the curved path 6A (or keep them in the retreating/protruding state).

As shown in FIG. 9 , in the second conveying state S2, based on the detecting part 73 detecting the conveying of the sheet P by the downstream side rollers pair 43, the first driving part 71 protrudes the first rib 44 into the curved path 6A, and the second driving part 72 retreats the second rib 45 from the curved path 6A. Specifically, the detecting part 73 sends a detection signal indicating that the sheet P is detected, to the controller, and the controller, upon receiving the detection signal (the detection result) from the detecting part 73, controls the first driving part 71 to protrude the first rib 44 into the curved path 6A, and controls the second driving part 72 to retract the second rib 45 from the curved path 6A (or keep them in the retreating/protruding state).

When the conveying of the sheet P proceeds and the detecting part 73 no longer detects the sheet P, the controller controls the first driving part 71 to retract the first rib 44 from the curved path 6A and controls the second driving part 72 to protrude the second rib 45 into the curved path 6A (see FIG. 8 ).

According to the medium guiding device 37 according to the third embodiment described above, the same effect as that of the medium guiding devices 35 to 36 according to the first to second embodiments can be obtained, for example, the generation of impact noise sound accompanying the springing up of the rear end of the sheet P can be suppressed while ensuring the smooth conveying of the sheet P in the curved path 6A.

In the medium guiding device 37 (the interlocking part 48) according to the third embodiment, the first driving part 71 and the second driving part 72 are each the servo motor, but is not limited to this, and may be, for example, a solenoid capable of reciprocating a plunger (not shown). The detecting part 73 is not limited to the reflection-type optical sensor, and may be, for example, a transmission-type optical sensor, a capacitance sensor detecting a capacitance which changes when the downstream side rollers pair 43 holds the sheet P, or a camera or the like that photographs the sheet P (not shown). The detecting part 73 of the medium guiding device 37 according to the third embodiment may be employed as the detecting part 62 of the medium guiding device 36 according to the second embodiment (not shown).

The medium guiding devices 35 to 37 according to the first to third embodiments are provided in the curved path 6A in the downstream portion of the second conveyance path 6, but this disclosure is not limited to this. For example, the medium guiding devices 35 to 37 may be provided in a portion (see FIG. 1 ) curved in an approximately U-shape in the upstream side portion (near the sheet feeding cassette 3) of the first conveyance path 5. In this case, the sheet feeding rollers pair 40 is the upstream side rollers pair and the conveying rollers pair 41 is the downstream side rollers pair. In this way, the medium guiding devices 35 to 37 can be applied to any path in which the medium such as the sheet P is conveyed while being flexed.

[First Modified Example] The medium guiding device 35 to 37 according to the first to third embodiment are provided in the image forming device 1A, but this disclosure is not limited to this. For example, as shown in FIG. 10 , the medium guiding device 35 to 37 may be provided in an approximately U-shaped curved document conveyance path 30 of the image reading device 1B (the first modified example). In this case, the document conveying rollers pair 32 arranged on the upstream side portion of the curved portion is the upstream side rollers pair, and the document conveying rollers pair 32 arranged on the downstream side portion of the curved portion is the downstream side rollers pair.

[Second Modified Example] As shown in FIG. 11 , the multifunctional peripheral 1 is sometimes provided with a post-processing device 7 which aligns the multiple sheets P or bundles the aligned sheets P with staples. Inside the post-processing device 7, a post-processing conveyance path 8 is provided which continues from the first conveyance path 5 of the image forming device 1A. The medium guiding devices 35 to 37 according to the first to third embodiments may be provided in the post-processing conveyance path 8 curved in an approximately U-shape of the post-processing device 7 (the second modified example). In this case, the post-processing rollers pair 74 arranged on the upstream side of the curved portion is the upstream side rollers pair, and the post-processing rollers pair 74 arranged on the downstream side of the curved portion is the downstream side rollers pair.

In the medium guiding devices 35 to 37 according to the first to third embodiment (including the modified examples, the same shall apply hereafter), the first rib 44 and the second rib 45 are formed in an approximately cylindrical shape and are rotatable around the axes, but this disclosure is not limited to this. For example, at least one of the first rib 44 and the second rib 45 may be formed in a semicircular or trapezoidal shape, or provided non-rotatably (not shown). In addition, one first rib 44 and one second rib 45 are provided, but not limited to this, for example, a plurality of first ribs 44 (a plurality of second ribs 45) may be attached at intervals to a shaft extending in the front-and-rear direction (not shown).

The image forming device 1A described above is a monochrome printer, but it is not limited to this, and may be a color printer, a copy machine, a facsimile machine or the like. In addition, the image forming method of the image forming device 1A is an electrophotographic type, but it is not limited to this, and may be an inkjet type.

The description of the above embodiment shows one aspect of the media guiding device, the image forming device, the image reading device and the post-processing device related to the present disclosure, and the technical scope of the present disclosure is not limited to the above embodiments. The disclosure may be variously modified, replaced or transformed to the extent that it does not depart from the purport of the technical idea, and the scope of the patent claims includes all of the implementations that may be included within the technical idea. 

1. A medium guiding device comprising: an upstream side rollers pair which is provided on an upstream side in a conveyance direction of the medium from an apex of a curved path included in a medium conveyance path, and rotates while holding the medium to convey the medium; a downstream side rollers pair which is provided on a downstream side in the conveyance direction from the apex in the medium conveyance path, and rotates while holding the medium to convey the medium; a first rib which is provided on the downstream side in the conveyance direction from the upstream side rollers pair and on the upstream side in the conveyance direction from the apex, is configured to be protruded into and retreated from the curved path from an outside in a radial direction of the curved path, and comes into contact with the medium in a protruding state into the curved path; and a second rib which is provided on the upstream side in the conveyance direction from the downstream side rollers pair and on the downstream side in the conveyance direction from the apex, is configured to be protruded into and retreated from the curved path from an inside in the radial direction of the curved path, and comes into contact with the medium in a protruding state into the curved path; and an interlocking part which interlocks the first lib and the second rib so as to protrude and retreat them into and from the curved path, wherein in a first conveying state where the medium is conveyed while being held by the upstream side rollers pair and separated from the downstream side rollers pair, the interlocking part retreats the first rib from the curved path and protrudes the second rib into the curved path, and in a second conveying state where the medium is conveyed while being held by the downstream side rollers pair, the interlocking part protrudes the first rib into the curved path and retreats the second rib from the curved path.
 2. The medium guiding device according to claim 1, wherein, the second rib is retreated from the curved path by the medium conveyed while being held between the upstream side rollers pair and the downstream side rollers pair, and the interlocking part protrudes the first rib into the curved path interlocking with retreating of the second rib from the curved path.
 3. The medium guiding device according to claim 1, wherein, the first rib and the second rib are elastically protruded into and retreated from the curved path.
 4. The medium guiding device according to claim 1, wherein, the interlocking part includes: a first link part attached to the first rib and provided turnably around a first axis; a second link part attached to the second rib, provided turnably around a second axis, and coupled to the first link part turnably and slidably; and a biasing member biasing the first rib or the second rib directly or indirectly, wherein in the first conveying state, a biasing force of the biasing member causes the first link part and the second link part to be turned such that the first rib is retreated from the curved path and the second rib is protruded into the curved path, and in the second conveying state, the second rib is pressed by the conveyed medium and retreated from the curved path against the biasing force of the biasing member while tuning the second link part, and the first link part is turned while sliding relative to the second link part so as to protrude the first rib into the curved path.
 5. The medium guiding device according to claim 1, wherein, the interlocking part includes: a driving part which causes the first rib to protrude into and retreat from the curved path; a detecting part which detects the second rib retreated from the curved path; and a biasing member which biases the second rib so as to protrude into the curved path, wherein in the first conveying state, the driving part retreats the first rib from the curved path, and the second rib is biased by the biasing member to be protruded into the curved path, and in the second conveying state, the second rib is pressed by the conveyed medium and retreated from the curved path against the biasing force of the biasing member, and based on a fact that the detecting part detects the retreated second rib, the driving part protrudes the first rib into the curved path.
 6. The medium guiding device according to claim 1, whereinthe interlocking part includes: a first driving part which causes the first rib to protrude into and retreat from the curved path; a second driving part which causes the second rib to protrude into and retreat from the curved path; and a detecting part which detects that the downstream side rollers pair is conveying the medium, and in the first conveying state, the first driving part retreats the first rib from the curved path, and the second driving part protrudes the second rib into the curved path, and in the second conveying state, based on a fact that the detecting part detects conveying of the medium by the downstream side rollers pair, the first driving part protrudes the first rib into the curved path, and the second driving part retreats the second rib from the curved path.
 7. The medium guiding device according to claim 1, wherein, the first rib and the second rib are cylindrical, and provided to be turnable around the axes in contact with the medium.
 8. An image forming device comprising the medium guiding device according to claim
 1. 9. An image reading device comprising the medium guiding device according to claim
 1. 10. A post-processing device comprising the medium guiding device according to claim
 1. 